On Saturday, December 20, 2025, a major power outage struck San Francisco, plunging approximately 130,000 homes and businesses—about one-third of the city—into darkness. The blackout, triggered by an extensive fire at a Pacific Gas & Electric (PG&E) substation, knocked out traffic lights across large swaths of the northern and western neighborhoods, causing widespread gridlock and transit disruptions.
The outage had a particularly dramatic impact on Waymo’s fleet of driverless robotaxis. With traffic signals dark, many autonomous vehicles came to a halt at intersections, unable to confidently proceed. Videos circulating on social media showed clusters of Waymo cars—sometimes two to six at a single corner—stopped with hazard lights flashing, blocking roads and forcing human drivers to maneuver around them.
Waymo, which operates around 1,000 vehicles in the city, suspended its ride-hailing service Saturday evening after coordination with city officials, who cited the vehicles’ contribution to traffic congestion. A company spokesperson explained that while the cars are designed to treat non-functional signals as four-way stops, the scale of the outage caused prolonged stationary periods. No accidents or injuries involving Waymo vehicles were reported.
Massive power outage in San Francisco on Saturday left 130,000 shrouded in darkness
Wait until California makes you drive all electric vehicles. What happens when the grid shuts down? pic.twitter.com/M8vYaiNQau
— Anthony Brian Logan (ABL)
(@ANTHONYBLOGAN) December 22, 2025
The incident highlighted vulnerabilities in autonomous vehicle technology amid infrastructure failures. Tesla CEO Elon Musk noted on X that his company’s robotaxis were unaffected, though they currently require human supervision in California.
Power was gradually restored, with most customers back online by Sunday. Waymo resumed operations that afternoon, stating it is incorporating lessons from the event to improve resilience. The outage underscored ongoing debates about the readiness of driverless cars for real-world disruptions in a city increasingly reliant on them.
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